Chapter 1 Introduction
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CHAPTER 1 INTRODUCTION 1.1 Introduction Zinnia is a genus of beautiful ornamental plants. Novel flowers colors of this plant will be of great commercial and aesthetic value. It is not famous like chrysanthemum or sunflower. However, Zinnia hybrids were induced too many cultivars because it can be a cut flower in the flower markets of many countries. Zinnia is a cosmopolitan ornamental plant with a long history. Many breeding companies have induced new cultivars with different attractive morphological characters. Zinnia cultivar classification is complicated by the fact that the typical characters are of qualitative nature and under strong environmental control such as height, flower size and leaf shape. To overcome these problems, in the present research Zinnia species and cultivars were analyzed on the genotypic level (DNA content, DNA sequence). Furthermore, the hybrids of zinnias are propagated by seedling. So the seeds of zinnia plants are produced by cross-breeding of parents. Then it is difficult to conserve cultivars. In addition, in vitro culture is a type of propagation method that enables multiplication of plant and genetic variation to be observed in a relatively short time. Therefore the conditions required for in vitro culture of zinnia were determined because there is little information available on in vitro zinnia. The results from these studies can be used to generate basic data for manipulation of zinnia culture. 1 2 1.2 Literature review 1.2.1 Zinnia 1.2.1.1 Scientific classification Kingdom: Plantae Division: Magnoliophyta Class: Magnoliopsida Order: Asterales Family: Asteraceae Genus: Zinnia Species: Zinnia acerosa Zinnia angustifolia Zinnia anomala Zinnia elegans Zinnia grandiflora Zinnia haageana Zinnia maritima Zinnia peruviana Etc. 3 1.2.1.2 Origin/history of zinnia (wikipedia, 2007) Zinnia is a genus consisting of about 20 species of annual and perennial plants of family Asteraceae, originally from scrub and dry grassland in an area stretching from the Southwest to South America, but primarily Mexico. Even after seeds of zinnias were sent back to Europe in the 18th century, the plants were not much to look at. Named for German botanist Dr. Johann Gottfried Zinn (1727-1759), who wrote the first description of the flower, the genus Zinnia had to wait for the late 19th century to become more successful as a garden annual. Breeding by selection occurred in Germany, Holland, and Italy: 'Pumila Mixed' (precursors of the 'cut-and-come-again' zinnias) and two selections from that strain, 'Mammoth' and 'Striata', were brought to Europe and enjoyed great success with gardeners. But the start of the zinnia's real popularity began around 1920 when Bodger Seeds Ltd. introduced the dahlia-flowered 'Giant Dahlia'. John Bodger discovered it as a natural mutation in a field of 'Mammoth' and within the next few years selected the large, flat-flowered 'California Giant' from the strain. It was available in separate colors and was considered to be a new trend in plant habit and flower form. It won a gold medal from the Royal Horticultural Society of England. 4 1.2.1.3 The advantages of Zinnia 1) Gardening Zinnias are popular garden flowers and especially favored by butterflies, therefore zinnias are interested by many gardeners. They are usually grown from seeds, and preferably in fertile, humus-rich, and well-drained soil, in an area with full sun. They will reseed themselves each year. Zinnias also have an amazing number of colors. in fact, flowers come in almost every shade except blue. Most are solid, but some, in particular Z. haageana , are bicolor with a contrasting color at the tip of each petal. The colors include yellow, orange, cherry, pink, purple, scarlet, and white. Heights are an important consideration when planning a garden, and zinnias have growth habits to suit every need. The tall, 3- to 4-foot varieties are best for the middle or rear of a border or in a cutting garden. Dwarf plants grow 8 to 14 inches tall and do well in pots as well as at the front of a garden. Z. angustifolia plants reach only 8 to 15 inches in height with an equal spread. They are excellent in the ground, in pots or hanging containers and as summer-flowering ground covers. In addition, dry flower of zinnia are used to decorate in houses. Alka et al . (2003) studied process of the drying zinnia flower such as Z .angustifolia . Zinnia flowers were embedded in different materials just as sand, borax and silica gel and dried at different temperatures to find the appropriate environment to exhibit well- maintained flower shape, smooth petals and attractive color of zinnia flower. 5 2) Ethno botanical use Zinnia species are used as a medicinal herb in some rural regions in North America (Table 1.1). Table 1.1 Use of zinnia species. Scientific name Use Zinnia acerosa Diarrhea, swelling, aches Zinnia angustifolia Poison Zinnia elegans Anodyne, Menstruation Zinnia multiflora Eye Altschul Zinnia peruviana Anodyne, Digestive, Menstruation Zinnia grandiflora Stomachache, Cathartic Heartburn, Nose, throat and kidney trouble Bath for excessive sweating In addition, phytochem screening of Z. elegan s indicat s that it contains coumarin, tannins, alkaloids, cardiac glycosides, sitosterol and triterpenes. The alc ohol ext ractions of different parts of zin nia (leaves, stems and flowers) exhibit s estrogen like activity when it w as administered orally to ovariectomized female rats. The ext ractions of leaves and stems of zi nnia h ad a stimulatory effect on the isolated pregnant rat uterus, while the flower ext raction ha s much less activity (Sharada et al , 1995). 6 The major components of Z. elegans flowers consist of the followings: Germacrene D (12.4%) has been shown to be the major volatile component of several species of aster and is a sex stimulant of Periplaneta males that was isolated from various plant leaves (Kitamura et al. , 1976). The chemical structure is shown on Figure 1.1a. Myrcene (7-methyl-3-methyleneocta-1, 6-diene) (11.8%) is a triply- unsaturated hydrocarbon used as an intermediate for the manufacture of flavor and fragrance chemicals. The chemical structure is shown on Figure 1.1b. p-Cymene (9.1%) is one of the alkyl-substituted aromatic hydrocarbons which are found in volatile oils from over 100 plants. (Zoghbi et al. , 2000) Me CH 2 CHMe 2 I a) Gernacrene D b) Mycene Figure 1.1 The formula structure of Gernacrene D (a) and Myene (b) 7 1.2.1.4 The cultivars of Zinnia One of the reasons for the popularity of the zinnia is the cultivar diversity of its forms and colors. There are zinnias with white, cream, green, yellow, apricot, orange, red, bronze, crimson, purple, and lilac flowers; zinnias with striped, speckled and bicolor flowers; zinnias with double, semi-double and dahlia-like 'pompon' flowers; zinnias that range from dwarfs that do not exceed 6 in. (15 cm.) in height to cut flower that get 3 ft. (0.9 m.) tall. Over 100 cultivars have been produced since selective breeding started in the 19th century. New varieties are resistant to powdery mildew and other diseases. 'Old Mexico' likes the wild plant with single, daisy like flower heads with wide purple rays. The first tetraploid zinnia, called 'State Fair', came from Ferry Morse Seed Company in the 1950's. (Tetraploids exhibit larger flowers on stronger stems, vigorous growth, and increased disease resistance.) Dwarf Zinnia ( Zinnia haageana ) was introduced for example, cv. 'Persian Carpet' and cv. 'Old Mexico'. John Mondry, who was working at the time for W. Atlee Burpee Company found a plant in the field with flowers that had no petals but was composed entirely of female reproductive parts. They could form seeds only after being cross-pollinated. That discovery led the way to the dwarf F1 Hybrid cv. 'Peter Pan' series introduced from 1971 to 1980. Yoshiro Arimitsu and Charles Weddle (National Garden Bureau, 2007) bred seven separate colors that were recognized as AAS Winners, now sold by Goldsmith Seeds, a wholesale seed company. Bodger Seed Ltd introduced the F1 Hybrid cv. 'Ruffles' series (cv. 'Scarlet', AAS 1974; cv. 'Cherry' and 'Yellow', AAS, 1978, http://www.all-americaselections.org), developed by Mondry (who had resigned from Burpee) as cutting flower plants. 8 In 1999 the 'Profusion' zinnia, 'Cherry' zinnia and 'Orange' zinnia, from Sakata Seed Corporation won Gold Medals from AAS--the first in 10 years. They represent a breakthrough in breeding for zinnias. They are interspecific crosses; that is, the result of crossing two species, Z. angustifolia and Z. elegans . They represent the best of both: heat and humidity tolerance, disease resistance, easy maintenance (no deadheading of spent blooms required), pretty 2- to 3-inches single flowers, and compact growth (12 to 18 inches tall) (National Garden Bureau, 2007). 1.2.2 Propagation of zinnia 1.2.2.1 Traditional propagation Zinnia has been propagated by seed and stem cutting. Seeding is an easy method, with a high survival of plants compared to stem cutting. However, seed propagation, is difficult to maintain the characters because of out-crossing behavior of zinnia. The seed companies usually cross parents of zinnia and bring its seeds to culture for sale because the morphological characteristics of new cultivars are stable. a) Pests and diseases Zinnias are basically pest free. For years, though, they have been known to be affected by two fungal diseases: powdery mildew and alternaria blight. Alternaria blight causes reddish brown spots on both foliage and flowers. It is a problem in the tropical area more than any other areas. The types of herbicide protecting zinnia from pets and disease are Daconil, Dithane, Mancozeb, Tilt, Sulfur, Benlate, Comag, etc. The best defense against the fungus is prevention.